In the past, the phase relationship between two capacitive test points was determined based on voltage measurements at the capacitive test points. Ideally, the voltage difference between the two capacitive test points would be zero if in phase and significantly larger if out of phase. However, due to the fact that the test point capacitive divider ratio can vary significantly from one test point to another, a large voltage difference between the two capacitive test points could occur due to the capacitive divider ratio difference and not due to the phase angle difference between the two capacitive test points. Therefore, the wrong conclusion could be reached regarding the phase relationship between the two capacitive test points. Moreover the prior art devices used to measure the phase relationship have a very high input impedance, which makes these devices very sensitive to contamination on the capacitive test point insulation surface, thus, giving an inaccurate voltage reading at the capacitive test points.
In general, the capacitive test point systems operate in the range of 15 KV(kilovolts) to 35 kV (kilovolts). In the past, the devices used for measuring the voltage and phase angle relationships between the two capacitive test points are often known to indicate no presence of voltage at the capacitive test points due to factors such as contamination at the capacitive test point insulation surface and any defects in the capacitive test point system itself.
Thus, a need exists to detect the phase relationship between capactive test points independent of the capacitive divider ratio difference and the capacitive test point voltage accuracy. Also, there is a need for a capacitive test point voltage and phasing detector with a very low input impedance and also capable of accurately detecting the presence of voltage in the capacitive test points independent of the voltage range in the systems, independent of any contamination or defects that may occur in the systems.